Comparison of elastolytic activity in lung lavage from current, ex- and non-smokers.

Cigarette smokers have an increased risk of developing a wide variety of lung diseases compared to non-smokers, and there have been many studies of the possible biochemical changes underlying this increased susceptibility. However, although epidemiological and physiological studies have shown that in the ex-smoker, the risk of smoking-related lung diseases falls between that of current and non-smokers, the biochemical and cellular mechanisms responsible for this intermediate status have not been investigated. In the present study, therefore, the extracellular elastolytic activities in lung lavage fluid from current, ex- and non-smokers have been compared. Elastolytic enzyme activity was investigated, since it is significantly elevated in lung lavage from smokers, and because it has been implicated in the development of pulmonary emphysema. In the subjects studied, extracellular elastolytic activities in lung lavage from ex-smokers were intermediate between those from current and non-smokers. There was no correlation between the time of abstinence from smoking, or the number of pack-years smoked and the extracellular elastolytic activities in ex-smokers' lung lavage. Elastolytic activity may remain elevated in ex-smokers' lungs for a number of reasons, including the persistence of particulate matter which may activate phagocytic cells on the lung surface. The possible significance of the raised elastolytic activity remains to be fully determined.